In recent years, energy crisis has been becoming increasingly fierce all around the world and has become an important subject for the sustainable development of our nation and society. Building energy consumption accounts for about 30% of national total energy consumption of developed countries. Under the circumstance of energy-saving and emission-reduction, there is an increasing demand of energy-saving for engineering construction.
As shown in FIG. 1, existing building roofing systems, such as the accessible roofing in “ (Construction Atlas for Standard Designs of Buildings in South-central China)”, are formed by combination of multi-layered, multiple materials such as a substrate layer 1, a sloping layer 2, a leveling layer 3, a waterproof layer 4, a thermal insulation layer 5, an isolating layer 6, a protective layer 7, a decorative layer 8 and the like. Although they can achieve such functions as waterproofing, thermal insulation and heat preservation of the building roofing, the following obvious defects are inevitably present due to the multi-layer structure thereof:
1. Since they are comprised of a multi-layer structure with various kinds of materials, the construction process is complex and cumbersome, the material consumption is large, the construction period is long, professional constructors are needed, and costs are high;
2. Since materials used are mainly mortar, waterproof rolls, waterproof paint, heat preservation materials and other building materials, there is a huge burden for the bearing structure of the building, a large consumption of rebar materials and a large consumption of energy and building materials during construction;
3. Due to inconsistent expansion coefficients of materials in different layers, the structure of multi-layer stacking with different materials tends to cause roofing cracking and water leakage;
4. For a structure of multi-layer stacking, the outermost protective layer is mainly comprised of rigid materials such as cement mortar. Once an artificial or natural damage occurs in the roofing structure, it is difficult to be troubleshot and detected, and the only option is to remove it wholly and rebuild, which results in a large resource consumption and a high maintenance cost;
5. A large amount of unrecoverable materials are needed to be consumed during construction and maintenance of the existing roofing systems, and therefore many construction wastes are produced, which results in not only consumption of excessive resources, but also damage to the environment;
6. Most of the materials used in the existing roofing systems comprise inflammable materials, in particular waterproof and thermal insulation materials, which will even produce toxic fumes when they are burned and therefore have larger security risk.